schmunk



J. D- SCHMUNK 2,923,996 APPARATUS I FOR FORMING CONCRETE PIPES 2 Sheets-Sheet 1 Feb. 9,, 1960 Filed Aug. 8, 1957 INVENTOR. JOHN D. SCHMUNK ATTORNEY Feb. 9; 1960 J. D. SCHMUNK 2,923,996

APPARATUS FOR FORMING CONCRETE PIPES INVENTOR. JOHN D. SCHMUNK ATTORNEY United States PatentO APPARATUS FOR FORMING CONCRETE PIPES John D. Schmunk, Findlay, Ohio, assignor to The Hancock Brick and Tile Company, Findlay, Ohio, a corporation of Ohio Application August 8, 1957, Serial No. 677,138

1 Claim. CI. 25-36) This invention relates to the manufacture of concrete pipe and an object is to produce a new and improved apparatus for producing concrete pipe, such for example as pipe having a bell at one end, in such manner that not only can pipe be produced economically and efliciently but also that the inner wall of the pipe is compacted and is non-porous and smooth and resistant to hydrostatic pressure Another object is to utilize saturated steam to create a paste with the cement during forming of the concrete pipe for effecting improved characteristics for the pipe and particularly the inner wall thereof.

Other objects and advantages will hereinafter appear, and for purposes of illustration but not of limitation, an embodiment of the invention is shown on the accompanying drawings, in which Figure 1 is a diagrammatic view partly in longitudinal section and partly in elevation of a concrete pipe forming apparatus in which saturated steam is introduced during the forming of the pipe, the bell former being shown in the position when concrete is first fed into the mold; Figure 2 is an enlarged fragmentary longitudinal sectional view of the pipe mold shown in Figure 1, showing the bell former partly in section and retracted from the mold, the packer head having moved part way upwardly in the mold;

Figure 3 is a transverse sectional view substantially on the line 33 of Figure 2; and

Figure 4 is a top plan view of the bell former substantially on the line 4-4 of Figure 2.

The illustrated embodiment of the invention comprises an elongate cylindrical pipe mold which is preferably a two-part structure having an outwardly flared or hell end 11 at the lower end. The mold 10 is formed with flanges 12 at the top and bottom and the upperflange abuts against the underside of an apertured stationary cut off plate 13. The flange 12 at the lower end of the mold abuts against a similar cut off plate 14 which is stationarily mounted and centrally apertured. The hole 13a in the upper cut off plate 13 enables the concrete to be poured in any suitable manner into the mold 10 and the opening 14a in the lower stationary cut oif plate 14 is concentric with the mold 10 and is of such size as to admit a bell former 15 which can be moved axially upward into the lower end of the bell 11, substantially as shown in Figure 1, when the concrete is first introduced into the mold 10 and, after the bell portion is molded, is retracted from the plate 14, as indicated on Figure l.

The bell former 15 is carried by a concentric rotary drive shaft 16 which imparts rotary motion to the bell former while it is in operating position with respect to the mold 10. The bell former is generally of cup form and is provided with a plurality of cylindrically spaced troweling surfaces 18 which have an upward and inward taper of about 9 from the cylindrical outer surface of the bell former. It will be observed that each of the troweling surfaces 18 as viewed from above, extend from an inner point and in a curvilinear line outward to the peripheral 2,923,996 Patented F eb. 9, 1960 surface of a bell former and then a short distance in an arc concentric with the bell former terimnating in an abrupt shoulder. In this instance four of these troweling surfaces are employed. The central socket 19 of the bell former is of a size to receive the packer head, as will hereinafter appear. Near the inner end of each of the troweling surfaces is a radial outlet port 20 which provides for steam exhaust.

-Rotatable within the mold 10 and shiftable longitudinally thereof is a packer head 21 having at its lower end an inverted elongate cup-shaped cylindrical troweling portion or long bottom 22, the smooth cylindrical outer surface of which is spaced inwardly from the inner surface of the mold a distance approximately equal to the desired thickness of the pipe to be formed. At the upper end of the packer head and integral therewith are packing wings 23 which project outwardly, forcing itradially toward the mold walls. Between the wings 23 and the troweling portion 22 is a pair of lateral passages 24 which open into an annular groove 24a, these passages enabling saturated steam to be forced to the inside wall of the molded concrete pipe, as will be more fully hereinafter explained.

The packer head 21 is keyed to an elongate packer shaft 25 which is long enough to extend well into the mold 10 with a substantial portion on the outside connected to suitable mechanism (not shown) for imparting rotation thereto. The shaft 25 drives the packer head at the same peripheral speed as that of the bell former is, these parts rotating at approximately 1000 feet per minute. The lower end of the packer shaft 25 is reduced to provide a shoulder against which the packer head abuts, a nut 26 on the inside of the troweling portion 22 securing the packer head in position. At the lower end of the packer shaft and in registry with the lateral passages 24 are lateral ports 27 enabling the steam from the longitudinal passage 28 in the packer shaft to pass out into contact with the inner surface of the pipe being molded. The upper end of the packer shaft is connected by a steam hose 29 to a suitable source of steam, there being a rotating connection 31 between the hose and the free end of the packer shaft.

It will be understood that low pressure saturated steam is introduced into the longitudinal packer shaft passage 28 and this serves as a medium for effecting a smooth, non porous finish to the inside wall of the machine molded concrete pipe. The steam after passing through the hollow packer shaft 25, discharges laterally through the ports 27 to the transverse passages 24 in the packer head. In the first instance the steam is introduced to the inside of the bell and the newly formed pipe wall when the bell former 15 and the packer head are in the position shown in Figure 1. The moisture resulting from the saturated steam combines with the cement and produces a paste which is then smoothly distributed by the troweling action of the revolving troweling portion or long bottom 22 and the bell former. This produces a finish as above provided for the inside walls of the concrete pipe and as the packer head slowly moves upwardly and at the same time rotates, a surface is achieved which is highly impervious to hydrostatic pressure. The compaction and smooth troweling of the cement paste during the pipe forming operation is possible because of the action of the moist steam immediately in advance of the troweling portion or long bottom 22 as well as the troweling surfaces of the bell former. The saturated steam is of low pressure, a pressure of approximately four pounds per square inch being found to be satisfactory for obtaining the desired paste for application to the concrete material ahead of the troweling operation. It will be observed that the steam is admitted in the region between the wing packers 23 and the troweling portion or long bottom 22. The condensation caused by the temperature diiferential between the saturated g steam and the concrete material with which the steam comes in contact produces the desired moisture condition. It will be understood that the concrete pipe is gradually formed as the packer head moves upwardly finally and completely out of the mold 10 so that in a onepass the concrete bell ipe is completely formed and the inner surface formed to efiect a smooth, non-porous finish.

Numerous changes in details of construction, arrang ment and operation may be effected without departing from the spirit of the invention, especially as defined in the appended claim.

What I claim is:

Apparatus for forming concrete pipe comprising an elongate open ended mold adapted to receive a cement mixture at one end, a unitary paeker'head longitudinally shiftable within the mold and rotatable therein, said head having an elongate tubular troweling cylinder at the outer end and an exterior annular groove adjacent the inner end of the cylinder, there being radial passagesfin said head terminating in the inside of said groove, integral radially extending packing wings on the inner end of the packing head, and a hollow shaft for shifting and rotating said head and having lateral ports registering with said radial grooves, thereby enabling fluid introduced into the hollow shaft to be discharged into said annular groove for impingement on the inner wall of the pipe being formed.

References Cited in the file of this patent UNITED STATES PATENTS 1,117,466 Wewerka Nov. 17, 1914 1,223,602 Moir et al Apr. 24, 1917 1,752,627 Zehnder Apr. 1, 1930 1,838,546 Halstead Dec. 29, 1931 2,168,917 Perkins Aug. 8, 1939 2,178,015 Brunetti Oct. 31, 1939 2,525,275 Schmidt Oct. 10, 1950 2,537,977 Dulmage Jan. 16,1951 2,557,544 Kennison June 19, 195] 20 2,598,972 Ohappell June 3, 195 2 

